Method of preparing demethoxy



Patent'ed Nov. 3, 1953 METHOD OF PREPARING DIMETHOXY- DECADIENES Richard S. Urban, Philadelphia, Ba. Win10! t0. Bohm, & Haas Company, Philadelphia, a

corporation ofDelaware.

No, Drawing. Application June 8, 1951, Serial No. 230,685

This invention relates to, an improved process for the preparation of a mixture of isomeric dimethoxydecadienes, all of which isomers have the formula It is known that dimethoxydecadienes can be made by reacting two mols of a methoxychloro pentene with one mol of nickel carbonyl. The; instant invention resides in the. use of finely divided iron or nickel in place of the nickel carbonyl used heretofore. As a result of the use of finely divided iron or nickel the rate of reaction is greatly increased, the yields of the desired product are higher and the amounts of lay-products are markedly reduced. In addition, the operation employing either iron or nickel is much more easily carried out on a commercial scale.

When a methoxychloropentene, having the formula CH3O-C5Hs--Cl, reacts with finely divided iron or nickel the atoms of chlorine are removed and react with the iron or nickel to form iron chloride or nickel chloride, and the remaining organic radicals combine to form a dimethoxydecadiene having the formula The reactant, CH30--C5H8C1, which reacts with the iron or nickel to produce the dimethoxydecadienes is itself prepared most conveniently from butadiene and chloromethyl methylether by the method which is described in U. S. Patent 2,075,312 of March 30, 1937. A compound, 1- methoxy-5-chloro-pentene-3, is the main product which is obtained by the reaction of butadiene and chloromethyl methyl ether, but it should also be noted that relatively smaller amounts of position isomers and geometric isomers of this compound are formed simultaneously. The isomers can be separated by conventional means as fractionation if desired. The main compound, 1-methoxy-5-chloro-pentene-3, reacts with iron or nickel to form 1,10-dimethoxydecadiene-3,7 having the formula and a lesser amount of the isomers of this compound. The isomers of 1-methoxy-5-chloro-pentone-3 react in a similar way and simultaneously undergo allylic rearrangement so that they form 1,10-dimethoxydecadiene-3,7 together with the isomers of this compound. In turn, the isomers can be separated, if desired, by fractionation.

The reaction of methozqrchloropentenes with 3 Claims. (C1. 260-25615) divided iron. or nickel is carried out at tern.

peratures from about C.--or-p efe 1yr ta the refluxing temp a ure of: e reaction The. use of av solvent. is strongly recommended in order to facilitate the reaction, Alcohols in eneral. are good. sol ents a d o hese ethano is the best. Many other alcohols have been tud d and it has be n found that t ose containing; one to seven carbon atoms, such as butyl,

hexyl and benzyl alcohols have an advantage over the higher alcohols in that they can be more. readily and cleanly separated from the reaction, mixture by distillation. Other preferred solvents include acetonitrile, di ylfonnamide. pr

pionitrile, butyronitrile and dioxane.

The iron or nickel should he in finely divided form. While coarse metal filings can be used, it is found that. the yield of dimethoxydecadiene is relatively low and the. yield of by-products is objectionably high. Therefore, the iron and nickel should be so. finely divided as to pass through a No. 140. U. S. Standard sieve. since the oxides of iron or nickel inhibit the reaction. it is most desirable that the metals be pure.

Raney nickel, pyrophoric iron and hydrogen-reduced iron are recommended. At least one-half mol of either metal is employed per mol of methoxychloropentene. In fact an excess of the order ,of 10-s50% is desirable.

The maximum amount of the metals which can be used is limited only by economical and mechanical considerations.

The reaction is carried out under normal, supere, or sub-atmospheric pressure. For reasons of efiicienoy it is preferred to employ normal or super-atmospheric pressures.

The following examples in which all parts are by weight serve to illustrate the process of this invention.

Example 1 0ne-ha1f mol (67.5 parts) of a mixture of; iso-. merio methoxychl ropentenes, was dissolved in 80 parts of ethanol. (This mix, ture had been prepared by passing butadiene, at the rate of 216' parts (4 mols) per hour, into a mixture of 498 parts of methyl chloromethyl ether and 25 parts of zinc chloride at 12-20 C. over a period of three hours, after which the reaction product was washed and fractionally distilled to provide a yield of of a material identical with that made by the process of Example 2 of U. S. Patent 2,075,312.) The solution was stirred and blanketed with carbon dioxide while to it was added 16.8 parts (0.3 mol) of hydrogen-reduced iron of such a particle size as to pass through a No. 140 U. S. Standard sieve. The mixture was stirred vigorously and was heated to the refluxing temperature at which point it was held for 22 hours. It was then cooled and was shaken with 150 parts of water and 105 parts of diethyl ether. The ether layer was separated, was washed with water and was dried over a desiccant. The ether was removed by distillation and the crude product was then fractionally distilled. A 64% yield was obtained of a product which boiled at 92-96 C./2 mm. This material was a mixture of isomeric dimethoxydecadienes and its analysis conformed to that of a material having the formula, C12H22O2.

Example 2 By a procedure similar to that described in Example 1 above, 0.5 mol of a mixture of isomeric methoxychloropentenes was reacted while dissolved in 80 parts of acetonitrile with 0.3 mol of commercially available, powdered, hydrogen-reduced iron. The mixture was stirred, blanketed with carbon dioxide and was heated at refluxing temperature for four hours. The product was worked up in the manner described in Example 1 above and a 72% yield of isomeric dimethoxydecadienes was obtained.

When a smaller amount of iron (0.2 mol) was used the amount of low boiling material increased at the expense of the dimethoxydecadienes and about a 50% yield of the latter was obtained. When larger amounts of iron (up to 0.6 mol) were used, the rate of reaction was faster but the yields approximated those obtained with 0.3 mol of iron.

Example 3 The procedure of Example 1 was followed with two exceptions, namely that pyrophoric iron was employed and the reaction period was only three hours. A 70% yield of dimethoxydecadienes was obtained. Not only was the rate of reaction very rapid but no appreciable amount of low-boiling lay-products was formed.

Example 4 The procedure of Example 1 was followed with one exception, namely that 17.7 parts (0.3 mol) of Raney nickel was substituted for the iron. A 56% yield of dimethoxydecadienes was obtained.

In this invention a mixture of isomeric dimethoxydecadienes is ordinarily obtained and while the individual unsaturated ethers can be isolated from the mixture the separation is often unnecessary for the commercial utilization of the ethers. For example, the mixture of ethers can be hydrogenated and oxidized to a mixture of dicarboxylic acids including sebacic acid and isomers thereof. Here again, the isomeric acids can be separated but for the preparation of esters which are used as plasticizers or for the preparation of alkyd resins such a separation is not ordinarily necessary,

4 I claim: 1. A process for preparing a mixture of isomeric dimethoxydecadienes, all of which have the formula which comprises reacting a mixture of isomeric methoxychloropentenes, all of which have the formula, CH3OC5Ha-C1, while dissolved in a solvent from the class consisting of acetonitrile and dimethylformamide, with finely divided iron at a temperature from 20 C. to the refluxing temperature of the mixture, said iron being in such a finely divided form as to pass through a No. U. S. Standard sieve and being present in an amount equal to at least one-half mol per mol of said methoxychloropentenes.

2. A process for preparing a mixture of isomeric dimethoxydecadienes, all of which have the formula CHaO-CmHrc-OCH:

which comprises reacting a mixture of isomeric methoxychloropentenes, all of which have the formula, CH30C5Hs--C1, while dissolved in dimethylformamide, with finely divided iron at a temperature from 20 C. to the refluxing temperature of the reaction mixture, said metal being in such a finely divided form as to pass through a No. 140 U. S. Standard sieve and being present in an amount equal to at least one-half mol per mol of said methoxychloropentenes.

3. A process for preparing a mixture of isomeric dimethoxydecadienes, all of which have the formula which comprises reacting a mixture of isomeric methoxychloropentenes, all of which have the formula, CH3OC5Ha-C1, while dissolved in acetonitrile, with finely divided iron at a temperature from 20 C. to the refluxing temperature of the reaction mixture, said metal being in such a finely divided form as to pass through a No. 140 U. S. Standard sieve and being present in an amount equal to at least one-half mol per mol of said methoxychloropentenes.

RICHARD S. URBAN.

References Cited in the file of this patent UNITED STATES PA'I'EN'I'S Number Name 1 Date 2,570,887 Tabet Oct. 9, 1951 OTHER REFERENCES Hoi et al.: Journal of Organic Chemistry, vol. 14, pages 1023-35, March 1949. Abstracted in Chemical Abstracts, vol. 44, page 3472i.

Spencer et al.: Proceedings of Chemical Society, vol. 26, page 118. Abstracted in Chemical Abstracts, vol. 5, page 868, 

1. A PROCESS FOR PREPARING A MIXTURE OF ISOMERIC DIMETHOXYDECADIENES, ALL OF WHICH HAVE THE FORMULA 